Interferometry in the evaluation of precorneal tear film thickness in dry eye.

PURPOSE: To compare tear film thickness between normal subjects and aqueous tear deficiency dry eye patients by tear interferometry.

DESIGN

Prospective case-control study.

METHODS

Central precorneal tear film thickness was measured noninvasively using an interference thin-film thickness measurement device (Quore MSPA1100; Mamiya-OP). Tear film thickness of 14 eyes from 14 normal subjects and of 28 eyes from 28 aqueous tear deficiency dry eye patients were compared along with noninvasively measured tear meniscus height, DR-1 (Kowa) dry eye severity grading, fluorescein and rose bengal staining scores, tear film break-up time, and Schirmer test results. Among dry eye patients, 13 eyes underwent punctal occlusion, and tear film thickness was compared before and after the surgery.

RESULTS

Tear film was significantly thinner in dry eye patients (2.0 ± 1.5 μm) than normal subjects (6.0 ± 2.4 μm; P < .0001). Tear film thickness showed good correlation with other dry eye examinations. After punctal occlusion, tear film thickness increased significantly from 1.7 ± 1.5 μm to 4.9 ± 2.8 μm (P = .001) with the improvement of tear meniscus height, fluorescein and rose bengal staining scores, tear film break-up time, and Schirmer test values.

CONCLUSIONS

Interferometric tear film thickness measurement revealed impaired precorneal tear film formation in aqueous tear deficiency dry eyes and was useful for showing the reconstruction of tear film after punctal occlusion surgery. Interferometry of precorneal tear film may be helpful for the evaluation of aqueous tear deficiency in conjunction with other dry eye examinations.